Previously: Parts I, II

A small update to my herd immunity tracker. The main change is that the data now accounts for the fact that people previously infected are getting vaccinated. I assume that past infection and vaccination are uncorrelated. This means that if, on one day a state has an estimated total infection rate of 30%, 30% of the people vaccinated on that day will have previously had the virus. The '% Infected and Vaccinated' data only refers to people who were infected then vaccinated, not vaccinated and contracted the virus. I'm not yet modeling those who get infected after vaccination.

Infection and vaccination are not happening to random samples of the population, but I think assuming the groups are uncorrelated is a good first approximation. The main groups currently receiving the vaccine are healthcare workers, essential workers, seniors, and those with preexisting conditions. While the latter groups have likely been taking higher than average precautions (and thus have lower infection rates than the overall population), healthcare and other essential workers are some of the most exposed to the virus and will thus have higher than average infection rates.

As of February 7th, accounting for previous infection among the vaccinated lowers the estimate of immunity from 37.2% to 34.8% of the US population.

The other change is a slider to make it possible to examine the data over smaller time periods. By default, the window is set from the first day vaccines were available in the US (December 14th, 2020) to the most recent day of data, but you can use the slider to change the window to look back before the vaccine rollout or a shorter period after rollout.

Data as of 2021-03-07
State Estimated % Infected (Only) Estimated % Infected & Vaccinated % Vaccinated (Only) Estimated % Immune
United States 24.5% 4.9% 12.8% 47.0%
Alaska 15.2% 4.5% 20.1% 44.4%
Alabama 29.3% 4.6% 9.8% 48.5%
Arkansas 32.0% 5.6% 10.6% 53.8%
Arizona 31.0% 7.1% 12.4% 57.7%
California 21.9% 4.7% 13.6% 44.8%
Colorado 19.9% 4.1% 14.1% 42.2%
Connecticut 21.0% 6.1% 18.0% 51.3%
District of Columbia 17.0% 4.0% 16.5% 41.5%
Delaware 24.2% 4.7% 13.1% 46.7%
Florida 25.1% 4.9% 12.7% 47.6%
Georgia 30.1% 4.2% 9.2% 47.7%
Guam 18.6% 4.8% 16.4% 44.6%
Hawaii 4.7% 1.0% 18.0% 24.8%
Iowa 24.7% 5.9% 14.0% 50.5%
Idaho 28.0% 5.2% 11.2% 49.7%
Illinois 25.1% 5.4% 12.9% 48.9%
Indiana 26.0% 5.0% 11.8% 47.8%
Kansas 27.8% 5.3% 11.3% 49.7%
Kentucky 24.9% 5.1% 13.4% 48.6%
Louisiana 27.9% 5.0% 11.1% 49.2%
Massachusetts 21.4% 5.4% 15.9% 48.1%
Maryland 17.6% 3.5% 14.0% 38.6%
Maine 7.8% 1.7% 18.0% 29.1%
Michigan 19.8% 3.9% 13.4% 41.0%
Minnesota 21.7% 5.1% 14.7% 46.5%
Missouri 22.5% 4.4% 12.4% 43.8%
Northern Mariana Islands 0.7% 0.2% 20.8% 22.5%
Mississippi 33.2% 6.3% 10.4% 56.2%
Montana 24.8% 5.9% 14.3% 50.9%
North Carolina 22.4% 4.3% 13.1% 44.1%
North Dakota 29.8% 8.7% 14.5% 61.7%
Nebraska 27.9% 6.0% 12.4% 52.3%
New Hampshire 13.9% 3.1% 16.7% 36.8%
New Jersey 33.3% 7.1% 11.9% 59.4%
New Mexico 20.9% 6.4% 18.1% 51.9%
Nevada 27.1% 5.4% 11.9% 49.8%
New York 29.8% 5.9% 11.9% 53.4%
Ohio 23.0% 4.5% 12.7% 44.7%
Oklahoma 29.3% 7.0% 13.5% 56.7%
Oregon 8.9% 1.8% 15.9% 28.3%
Pennsylvania 21.1% 4.2% 13.6% 43.1%
Puerto Rico 12.5% 1.7% 10.8% 26.6%
Rhode Island 27.5% 7.0% 14.5% 56.0%
South Carolina 28.8% 5.1% 11.3% 50.2%
South Dakota 37.2% 11.1% 12.8% 72.1%
Tennessee 33.2% 5.7% 9.7% 54.3%
Texas 28.7% 4.7% 10.8% 48.9%
Utah 27.4% 4.6% 10.5% 47.1%
Virginia 19.3% 3.9% 14.3% 41.4%
Virgin Islands 6.9% 1.0% 13.7% 22.6%
Vermont 5.6% 1.1% 19.0% 26.8%
Washington 12.6% 2.6% 15.3% 33.0%
Wisconsin 27.8% 6.5% 12.9% 53.6%
West Virginia 17.1% 4.0% 16.6% 41.6%
Wyoming 23.9% 5.4% 13.9% 48.7%